“It depends on what happens with Turkey’s acquisition of the S-400 missile system, that will have some impact,” Sen. Jeanne Shaheen, D-N.H., told Al-Monitor. “We’re still discussing it.”

At issue is Turkey’s pending acquisition of Russia’s S-400 missile defense system and its continued detention of US citizens and locally employed consular staff.

For now, Senate Majority Leader Mitch McConnell, R-Ky., is refusing to take up spending legislation that doesn’t fund President Donald Trump’s proposed border wall with Mexico. Still, lawmakers in both chambers are eyeing Ankara’s next moves as they weigh whether to move forward with the Turkey provisions again this year.

House Democrats voted mostly along party lines last week to pass a spending bill that hits Turkey with arms sales bans and sanctions. The bipartisan provisions originated in the Republican-held Senate last year but did not clear the House at the time.

Relations between Washington and Ankara temporarily thawed last year following the release of US pastor Andrew Brunson. But Congress is still putting Ankara on notice.

As members of the foreign aid panel, Shaheen and Sen. James Lankford, R-Okla., worked across the aisle last year to include the arms sales restrictions and sanctions on Turkey in spending legislation. The Shaheen-Lankford provisions include a ban on the transfer of F-35 aircraft to Turkey unless the Trump administration certifies that Ankara is not moving forward with the S-400 purchase from Russia.

Turkey participates in a F-35 co-production program with the United States and several other countries. The Pentagon reported to Congress last year that kicking Turkey out of the co-production program could delay the delivery of between 50 and 75 F-35s by up to two years.

Moving ahead with the S-400 sale could also subject Turkey to US sanctions under the 2017 Countering America’s Adversaries Through Sanctions Act. That bill requires the Trump administration to sanction countries doing business with designated Russian defense contractors, including Almaz-Antey, which produces the S-400s.

Shaheen and Lankford have also pushed for narrower sanctions in the spending bill, which would place visa bans on senior Turkish officials involved in the detention of US citizens.

That was before Turkey released Andrew Brunson, a US pastor whose incarceration galvanized Republicans’ evangelical base. Turkey, however, continues to detain another US citizen, NASA contractor Serkan Golge. While Trump’s lack of focus on Golge stands in stark contrast to his vocal calls to release Brunson, Shaheen told Al-Monitor that Ankara’s detention of the scientist and other locally employed US consular staff “continues to be a concern.”

Finally, the spending bill would ban US weapons sales to President Recep Tayyip Erdogan’s personal bodyguards unless members of his security detail involved in beating protesters during his 2017 visit to Washington return to stand trial in US courts. Four of them still have cases pending in US courts after the Trump administration dropped charges on 11 others.

Congress aside, the Trump administration itself continues to struggle to navigate a dicey alliance.

Relations appeared set to improve after Erdogan reportedly convinced Trump to withdraw US troops from Syria last month, paving the way for a Turkish offensive against the US-backed Kurdish People’s Protection Units, which Ankara deems a terrorist group.

However, the administration has since walked back an initial 30-day timeline for withdrawal and demanded assurances that Ankara refrain from attacking the Syrian Kurds. An irate Erdogan responded by canceling a meeting with national security adviser John Bolton and instead publicly lambasted him before parliament.