In the code above, what is the primary concurrency issue that may occur when two threads call increment() concurrently?

public class Counter {
    private int count = 0;
    public void increment() {
        count++;
    }
    public int getCount() {
        return count;
    }
}

public class CounterTest {
    public static void main(String[] args) throws InterruptedException {
        Counter counter = new Counter();
        Thread t1 = new Thread(() -> { for (int i = 0; i < 1000; i++) counter.increment(); });
        Thread t2 = new Thread(() -> { for (int i = 0; i < 1000; i++) counter.increment(); });
        t1.start();
        t2.start();
        t1.join();
        t2.join();
        System.out.println(counter.getCount());
    }
}