Donald Trump and Elizabeth Warren are at war — on Twitter.

Trump can call US Sen. Elizabeth Warren (D-MA) all the names he wants; it's not going to stop her from challenging the presumptive Republican nominee.

On Wednesday, Warren unleashed a fresh tweetstorm targeting Trump, firing off a string of seven attacks. She implied that Trump is sexist for calling her a "basket case" and went on to hit him on policy.

We get it, @realDonaldTrump: When a woman stands up to you, you’re going to call her a basket case. Hormonal. Ugly. — Elizabeth Warren (@elizabethforma) May 11, 2016

Warren has taken on the role of Twitter attack dog, as the New York Times puts it, going after Trump aggressively with some of the Hillary Clinton campaign's favored lines, including that Trump is simply unfit to be president:

.@realDonaldTrump: Your policies are dangerous. Your words are reckless. Your record is embarrassing. And your free ride is over. — Elizabeth Warren (@elizabethforma) May 11, 2016

It was a call for action from Warren, demanding Trump "answer for his dangerous ideas":

When asked what gov should stop doing, @realDonaldTrump said overseeing banks! How can you be tough on Wall Street by letting them off? — Elizabeth Warren (@elizabethforma) May 11, 2016

You're so concerned about Wall Street, @realDonaldTrump, that you say you’d "absolutely" repeal Dodd-Frank? — Elizabeth Warren (@elizabethforma) May 11, 2016

You feel so much for people with college debt, @realDonaldTrump, that you raked in millions scamming students with Trump University? — Elizabeth Warren (@elizabethforma) May 11, 2016

You care so much about struggling American workers, @realDonaldTrump, that you want to abolish the federal minimum wage? — Elizabeth Warren (@elizabethforma) May 11, 2016

Trump employed his typical strategy in response: go personal. He brought up a four-year-old controversy in which Warren claimed, but did not substantiate, Native American heritage.

Goofy Elizabeth Warren didn’t have the guts to run for POTUS. Her phony Native American heritage stops that and VP cold. — Donald J. Trump (@realDonaldTrump) May 11, 2016

It's been his choice anecdote for Warren on the campaign trail, since the Massachusetts senator has increasingly gained traction with Democratic voters, many of whom are calling on Democratic frontrunner Hillary Clinton to add her to the ticket.

Goofy Elizabeth Warren is weak and ineffective. Does nothing. All talk, no action -- maybe her Native American name? — Donald J. Trump (@realDonaldTrump) May 7, 2016

It’s Trump’s latest personal social media attack, having taken a similar route with Ted Cruz’s wife, Heidi Cruz, and Breitbart reporter Michelle Fields, who claimed Trump’s campaign manager had physically assaulted her.

Warren has long been critical of Trump, calling him a "loser" in a Facebook post in March, and again after the Indiana primaries, condemning him for his "racism, sexism, and xenophobia."

And regarding Trump's epithet for her: "Weak!"