Trump's morning Twitter post was his most direct statement on the objective of the meeting, though his son and others have said it was to gather damaging information on the Democratic candidate. He went on to distance himself from Trump Jr. and the meeting: "I did not know about it!"
Mr Sekulo told ABC the Trump team had not broken any specific laws in their election campaigning.
"Well, the question is, how would it be illegal?"
At the time, in July 2017, Trump offered a similar comment to the one he made on Sunday, dismissing the meeting with a Russian lawyer promising dirt on his political opponent as no big deal. Working with a foreign national with the intent of influencing a US election could violate multiple laws, according to legal experts.
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Russian lawyer Natalia Veselnitskaya speaks during an interview in Moscow, Nov. 8, 2016.
"I wasn't involved in the statement drafting at all, nor was the president", Sekulow claimed in July 2017.
That misleading statement, which the White House later admitted was drafted with the president's help, said the Trump Tower meeting was about a law governing adoptions from Russian Federation rather than a meeting to get negative information about Clinton.
"I am comfortable in saying this: if there was evidence, strong evidence of collusion, I guarantee you it would have been leaked by now", the Republican senator said.
At that time, Russian officials were under USA sanctions.
"OK, totally legal, actually great, everybody does it, I wasn't there, put my son in jail", the host said, mimicking the tweet's tone. It's equally as shocking that Trump would ignore the advice of his inner circle.
"The president has been clear that he wants to interview", he said.
One of the president's personal lawyers said on Sunday that if Trump is subpoenaed by the special counsel, his lawyers will attempt to quash it in court. At that point, he said, Trump's attorneys would raise what Trump has alleged are Mueller's "conflicts of interest".
The fusillade of tweets came from Bedminster, Trump's golf course, where he is ensconced in a property that bears his name at every turn and is less checked in by staffers. Sekulow also raised the point that Mueller applied to be Federal Bureau of Investigation director - a job he held under previous administrations - and was turned down before being appointed special counsel by Deputy Attorney General Rod Rosenstein. Last week, Trump's national security team said Russian Federation was behind "pervasive" attempts to interfere in November 2018 congressional elections.
"But there's not a situation where it's just you say yes", Sekulow said.
Mueller would have the option to issue a subpoena compelling the president to testify if Trump chose not to be interviewed.