WASHINGTON • President Donald Trump authorized sanctions and raised steel tariffs on Turkey on Monday while threatening more powerful financial penalties if Ankara continued a military offensive in northern Syria launched after Trump decided to withdraw U.S. troops from the region.

Trump also spoke separately with President Recep Tayyip Erdogan of Turkey and Kurdish Commander Mazloum Abdi and urged them to negotiate an end to the violence, administration officials said. Trump, calling for an immediate cease-fire, tapped Vice President Mike Pence and White House national security adviser Robert O’Brien to lead a delegation to Turkey to seek a resolution to the conflict.

The administration’s first punitive actions against Turkey and its effort to start talks came amid widespread criticism on Capitol Hill that Trump’s decision left Kurdish militias that had aided the U.S.-led fight against Islamic State open to attack. Meanwhile, Democratic and Republican lawmakers said they plan to speed through their own sanctions package starting Tuesday.

“I am fully prepared to swiftly destroy Turkey’s economy if Turkish leaders continue down this dangerous and destructive path,” Trump said Monday. “Unfortunately, Turkey does not appear to be mitigating the humanitarian effects of its invasion.”

Administration officials said Trump wouldn’t be willing to send a delegation to Ankara on short notice if he didn’t think a cease-fire was possible. They pushed back on the notion that the U.S. was responsible for the current chaos along the Turkish-Syrian border, insisting that Turkey alone is to blame.

Syrian military convoys moved Monday into towns along the northern border with Turkey, emboldened by a newly forged accord with Kurdish authorities. Syrian soldiers raised the national flag in Ain Eissa, a town north of Raqqa — Islamic State’s former de facto capital — where thousands of U.S.-backed fighters had trained at a military base.

The administration has signaled that the U.S. could start with sanctions that don’t inflict much damage, but could then be ramped up to a level that would cripple the Turkish economy, including severing access to U.S. markets.

The sanctions the U.S. Treasury imposed Monday target Turkey’s Defense, Interior and Energy ministers and their departments. The U.S. warned that any person or business doing business with them risked also being blacklisted, including banks losing access to dollar markets. Trump also said that the U.S. would raise the tariff rate on steel imported from Turkey to 50%, after lowering the rate from that level back in May.

The Treasury said it would issue waivers to ensure sanctions didn’t disrupt the entire country’s energy needs, and will allow officials and contractors conducting business for the U.S. government to work with the blacklisted officials and offices.

The U.S. continued to withdraw military forces from front-line bases in northern Syria on Monday after evacuating U.S. diplomats overnight Sunday, current and former administration officials said.

Trump said Turkey’s military incursion threatens to destabilize the region, risks jeopardizing a successful U.S. campaign against Islamic State, deepens a widespread humanitarian crisis, and sets the stage for possible war crimes.

The U.S. is “at risk of being engulfed in a broader conflict,” Defense Secretary Mark Esper said. “Therefore, at the president’s direction, the Department of Defense is executing a deliberate withdrawal of U.S. military personnel from northeast Syria.”

“Turkey must immediately cease its unilateral offensive in northeast Syria and return to a dialogue with the United States on security” in the region to avoid suffering further sanctions, Secretary of State Mike Pompeo said late Monday.

Turkey’s embassy in Washington didn’t respond to requests for comment on the sanctions.

The administration’s threat to use it most potent financial weapon — banning Turkish banks from accessing the U.S. markets and the world’s most important currency — risks imposing much deeper damage on Turkey’s economy than Monday’s actions do. Trump also said the U.S. will halt negotiations on a potential $100 billion trade deal.

Lawmakers on Capitol Hill said they are preparing legislation that could require the White House to impose tougher sanctions, fearing Trump may not follow through with his threats.

House Speaker Nancy Pelosi, D-Calif., said she had spoken with Sen. Lindsey Graham, R-S.C., about putting together a bipartisan, bicameral sanctions package that is stronger than what the White House is considering. Graham, a close ally of the president who has sharply criticized his decision to move troops out of northern Syria, echoed Pelosi’s statement and wrote in a tweet that he would move to “draft sanctions and move quickly.”

After the planned Ankara talks were announced, Graham said he had joined Trump on the calls with leaders in the conflict and said officials should be given “reasonable time and space to achieve our mutual goals.”

The U.S. began repositioning some 1,000 troops in northern Syria last week, and Turkish forces quickly moved into the area, battling Kurdish militia.

Turkey-backed Syrian rebel fighters at the border town of Tel Abyad, Syria, wave their weapons Monday.

REUTERS