Former national security adviser Michael Flynn allegedly plotted to abduct a Turkish cleric, according to a Wall Street Journal report.
The arrest of a Turkish employee of the U.S consulate in Turkey has led both countries to temporarily stop issuing new visas.
Thousands marched in protest of the Turkish president's crackdown on dissent since a failed coup last year.
Amnesty International said seven activists and the director of its branch in Turkey were arrested "blatantly without cause."
Turkey's Parliament offered the diplomatically isolated nation of Qatar a show of support by speeding up a bill to send troops to the country.
The country's new constitution allows the president to join political parties again, so Erdogan became the head of Parliament's largest party.
President Donald Trump inherited a souring relationship with Turkey's president, who doesn't like one U.S. method for dealing with ISIS.
The YPG is a dominant force within the Syrian Democratic Forces.
He said he had photos and video to prove it.
No group has claimed responsibility for the blast yet, but ISIS and Kurdish militants have carried out similar attacks before.
Suspects can now be held without charges for 30 days. Some have questioned how the government is so prepared for the aftermath of the coup attempt.
Turkey's new state of emergency could suspend most of the rights and freedoms set out in the country's constitution.