Turkish President Recep Tayyip Erdogan has walked all over the US in the past few weeks, and President Donald Trump let him.

Trump pulled US troops from northeast Syria earlier this month, effectively abandoning US-allied Kurdish forces to a Turkish invasion, with reports of war crimes committed against the Kurds.

Republican Sen. Mitt Romney of Utah said: "Are we so weak and so inept diplomatically that Turkey forced the hand of the United States of America? Turkey?!"

The Trump administration negotiated a so-called ceasefire with Turkey on Thursday that suspends military operations for five days to allow Kurdish forces to withdraw.

The agreement means the US has effectively negotiated the surrender of the Kurds in a conflict that was sparked by Trump's decision.

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Turkish President Recep Tayyip Erdogan's recent actions signal he does not respect the US, and does not fear any significant repercussions despite tough talk from President Donald Trump.

Last week, Turkey invaded Syria to go after Kurdish forces who were, until recently, closely allied with the US in the fight against ISIS.

This came several days after Trump and Erdogan spoke on the phone and the White House subsequently announced the US was moving to withdraw troops from northeast Syria ahead of the Turkish incursion. Trump said he did not endorse the invasion, but by withdrawing troops he'd given Erdogan a green light to move forward with it.

Read more: Trump's 'great for everybody' ceasefire deal in Syria gives Turkey everything it wants in exchange for virtually nothing

During a press conference in Japan months before, Trump boasted about how he'd stopped Erdogan from going into Syria to "wipe out" the Kurds. Fast-forward to October and Trump abruptly stepped aside to allow Erdogan to target a group that lost 11,000 fighters as they served as America's battering ram in the effort that crushed ISIS's caliphate.

The credibility of the US is now down the tubes, US lawmakers and former officials say. Even Republicans are speaking out, with GOP Sen. Mitt Romney blasting Trump and the US as being "so weak and diplomatically inept" to capitulate to Turkey and calling for public hearings on the matter.

"We're a laughing stock. We're the butt of jokes. Nobody is going to want to partner with us now," Democratic Sen. Chris Murphy told Insider on Tuesday. "And I don't know that a Democratic president can recover from this. It's just devastating what President Trump has done to American credibility."

Trump with Turkish President Tayyip Erdogan during the G20 leaders summit in Osaka, Japan, June 29, 2019. Kevin Lamarque/Reuters

Trump gave Erdogan everything he wants

Trump wrote a letter to Erdogan the day after Turkey launched the invasion into Syria, urging him not to be a "tough guy." The Turkish leader, widely regarded as an autocrat and enemy to democracy, reportedly threw it into the trash.

Last Friday, US forces in northern Syria came under fire from Turkish artillery. Though no Americans were hurt, some US officials believed this was intentional and meant to push the US out. This would be an astonishingly bold move, given the US and Turkey are technically allies as fellow NATO members.

Subsequently, Trump told the Pentagon to begin withdrawing the remaining 1,000 US troops in northern Syria.

The Turkish invasion has sparked a humanitarian crisis in Syria, and over 300,000 have reportedly been displaced since it began. Meanwhile, Turkish-backed Syrian Arab militants have reportedly committed war crimes against the Kurds. ISIS is also regrouping, and Russia has won a major geopolitical victory.

'Turkey forced the hand of the US'

On Thursday, the Trump administration announced a deal had been met with Turkey for a five-day suspension in military operations in northern Syria to allow Kurdish forces to withdraw. This came after Vice President Mike Pence traveled to Turkey to meet with Erdogan. Pence characterized the agreement as a ceasefire, but the Turkish foreign minister promptly disputed this.

The agreement means the US has effectively negotiated the surrender of the Kurds in a conflict that was sparked by Trump's decision. Turkey gets everything it wants: Kurdish forces it views as terrorists are ceding territory and the US has agreed to lift recently imposed sanctions once a permanent ceasefire is established.

Read more: Trump compared Turkey attacking the Kurds to 'two kids in a lot': 'You have to let them fight, and then you pull them apart'

A day after the House overwhelmingly voted in favor of a resolution condemning Trump's Syria retreat, the president celebrated the deal and praised Erdogan, calling him a "hell of a leader."

But many US lawmakers, including some Republicans, are not satisfied and feel Turkey has walked all over the US.

Romney said: "The announcement today is being portrayed as a victory. It is far from a victory."

He added: "Are we so weak and so inept diplomatically that Turkey forced the hand of the United States of America? Turkey?!"

Echoing views that have been shared by many of his colleagues over the past week, Romney went on to say: "The decision to abandon the Kurds violates one of our most sacred duties. It strikes at American honor. What we have done to the Kurds will stand as a bloodstain in the annals of American history."